Detection of Oxytetracycline Residuein Infant Formulaby High-Performance Liquid Chromatography)HPLC(.

Determination of drug residues in food is of great importance due to their toxicity. Long-term exposure with low level of drug residues could be important, especially in children. Based on document study, oxytetracycline )OTC) is a prophylaxis and treatment agent for great number of diseases and possesses a broad spectrum activity against many pathogenic organisms and can be toxic or cause allergic reactions in some hypersensitive individual's if the residues of drug exist in the infant formula. The previous studies show that using high-performance liquid chromatography (HPLC) is useful for OTC detection in milk. Therefore, we decided to measure OTC in infant formula. The purpose of this study was to investigate residual OTC in consuming infant formula using HPLC. The limit of quantification (LOQ) was 51 ng/mL. This result showed that the samples had no residues of OTC in infant formula from different companies.


Introduction
is specially manufactured to satisfy, by itself, the nutritional requirement of infants during formulas are of two basic types: milk-based and milk-free. Each type is available as concentrated liquid, ready-to-feed form and powdered varieties (2). The occurrence of antibiotic residues in infant formulas (milk-based) arising from its veterinary use is a case of concern to parents, pediatricians, nutritionists and particularly food control organizations worldwide, because of possible toxic or allergic reactions and the possibility that pathogenic organisms can be resistant to the antibiotics. It must be noticed that infants as target group (formula consumers) are more sensitive to above mentioned effects, so, these products should not contain contaminants or undesirable substances in amount which may represent a hazard to health of the infant (1, 3).
Tetracyclines (TC S ) are the most recurrent prescribed antibiotics since their discovery in the mid-1900s. They have played an important role in sustaining health among the physicians and veterinarians. The therapeutics has been of particular interest for their use in food producing animals because of their broad spectrum activity and low cost. They (TC S ) are used for preventing and controlling diseases and also as feed additives to promote the weight gain and to increase the produced milk as well. TC S are approved to be used in food producing animals with tolerances ranging from 0.7 to 2 PPM in commonly consumed animal tissue and products. Tolerances for less commonly consumed tissue reach 12 PPM (4, 5). TC S can be successfully determined in various biological matrices, using highthe reverse-phase mode, with different detection and mass spectrometry. The ultraviolet (UV) detection has low sensitivity, while mass spectrometry still requires costly instruments (3,6,7,8). In Iran, some studies have been carried out on the presence of tetracyclines in food and infant formula.
The present study was conducted to describe the development in validation of an analytical method in order to detect and determine the Oxytetracycline (OTC) residue in commerciallyavailable infant formula received in Food and

Experimental
A total of 30 samples of commercial infant formula were bought from supermarkets in Tehran grade solvents were obtained from sigma (sigma, USA). A standard stock solution of OTC was Working standard solutions were daily prepared. All solutions had to be wrapped in aluminum foil since OTC is unstable and often changes from yellow to brown with exposure to light.
The chromatographic analysis was carriedout in a Dionex high-performance liquid chromatograph (München, Germany and Sunnyvale, CA, USA) equipped with a Dionex P680 Pump and a Dionex Rodyne Valre Injector. The analytical column which operates at room temperature was ACE C18-A3681, 250×4.6 mm ID from Dionex, and the analysis involving UV detection was performed in a Dionex UVD 170U/340U UV/Vis absorbance detector (The wavelength of the UV-Visible detector was set at 355 nm). The Chromeleon (version 6.60, Dionex) software was used to control the system. At the stage of extraction, Boatto et al. and Hosseini M et al. method has been used (9, 7). system and peak area of OTC was plotted versus of r 2 = 0.995 and a calibration curve of (Y = 1.0946(x) + 0.0424) was concluded (Y = peak The results were expressed as mean ± RSD of (CV) for each concentration.

Results and Discussion
The average recoveries of OTC from milk samples were suitable (more than 75%) at three and 2). Results of precision and accuracy were in acceptable range. The percentage of correlation variation was lower than 6% .The limit of interferences by extracting and analyzing blank samples from different sources. The chromatograms recorded at 355 nm were free of interfering extraneous peak, in the extracts of blank as well as in spiked samples. The retention time of target compound was 6.6 min.
Tetracyclines (TC S ) are widely distributed In addition, Oxytetracycline (OTC) located in this family with a broad-spectrum bacteriostatic activity and applied in animal husbandry, is used to prevent the treatment of bacterial infections and increase growth rates .It could inhibited protein synthesis and cell growth of sensitive bacteria (8).
In response to protecting humans from the exposure to these drug residues in milk or infant formula, several European countries have in infant formula (1, 10, 11). In literature review, both microbiological and chromatographical methods have been described for monitoring tetracyclines in milk, infant formula and animal method for OTC determination in liquid samples. Results of our study showed that there are no residues of OTC in infant formula samples. Although, OTC residue in infant formula samples were not detectable, fairly low cost and broad spectrum activity of OTC indicates the need for the awareness of the toxic effect of this drug and other drugs. In addition, it is suitable that total average of TC S in milk and infant formula was evaluated. a suitable retention time (6.6 min) without any interfering extraneous peak. The results show that reliable assay of OTC in infant formula. It seems that this method would be useful for routine monitoring of OTC residues in infant formula. It  is necessary to have a comprehensive survey to determine the amount of drugs in products and indeed some rules are needed to be executed in this regard to minimize the contamination to the least possible amount and to preclude its adverse effect. Therefore, due to the importance of baby food and infant formula, more researches are to be conducted for designing quality improvement and safety of food stuff such as milk, infant formula and animal tissues from any drug residues.